AP BIOLOGY

Detailed explanation-1: -In general, DNA methylation represses transcription, and loss of methylation is associated with gene activation (4). DNA methylation can directly interfere with transcription factor binding in some cases (6).

Detailed explanation-2: -This chemical group can be removed through a process called demethylation. Typically, methylation turns genes “off” and demethylation turns genes “on.”

Detailed explanation-3: -DNA methylation regulates gene expression by recruiting proteins involved in gene repression or by inhibiting the binding of transcription factor(s) to DNA.

Detailed explanation-4: -DNA methylation may affect the transcription of genes in two ways. First, the methylation of DNA itself may physically impede the binding of transcriptional proteins to the gene, and second, and likely more important, methylated DNA may be bound by proteins known as methyl-CpG-binding domain proteins (MBDs).